(1) Field of the Invention
The present invention relates generally to transducers used to convert an acoustic signal to an electrical signal, and more particularly to a transducer using scattered laser light reflections from a pressure release boundary between two mediums of different acoustic characteristic impedance.
(2) Description of the Prior Art
Traditional transducers rely on piezoelectric materials to convert acoustic signals in the form of pressure waves into electrical signals. More recently, research and development has been undertaken in the area of laser optic transducers, or hydrophones. As an example of such a device, U.S. Pat. No. 5,504,719 to Jacobs recites a laser beam which is focused upon a small volume of water in which natural light scattering matter is suspended and which matter vibrates in synchronism with any sonic waves present. The vibration produces a phase modulation of the scattered light which may be recovered by optical heterodyne and sensitive phase detection techniques. These laser transducers suffer in that the particles scatter the laser light in all directions, thus significantly reducing the amount of scattered light reflected back to the transducer and making detection of an acoustic signal more difficult. When the flow around the transducer is increased, additional noise components are introduced further complicating signal detection.